Concave with adjustable openings

ABSTRACT

A concave section for a harvester is provided. The concave section includes a concave body having an upstream side, a downstream side, a leading end and a trailing end. The concave body defines an arcuate crop engagement face facing radially inwardly. A plurality of crop passage openings are defined through the arcuate crop engagement face. A cover is configured to at least partially cover at least some of the crop passage openings. The cover is carried by the concave body and is movable thereon between at least two different positions to adjust a degree of openness of at least some of the crop passage openings.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application claims the benefit of U.S. Provisional PatentApplication No. 62/690,258, filed Jun. 26, 2018, the entire teachingsand disclosure of which are incorporated herein by reference thereto.

FIELD OF THE INVENTION

This invention generally relates to a concave region of a rotary combineharvester and more specifically to concave sections thereof.

BACKGROUND OF THE INVENTION

A rotary combine harvester, that may be referred to as a harvester isutilized to harvest crop from a field, separate the grain from thematerial other than grain (MOG) and to dispense these materials from themachine appropriately. These harvester tasks are complicated anddifficult to accomplish. Indeed, not only do they need to be adapted toseparate many different types of grains from MOG but they must alsoaccount for different crop conditions and weather conditions in whichthe harvesters must operate in.

A rotary combine harvester's main threshing and separating systemconsists of a large cylindrical rotor driven by the machine's mainengine. There are threshing elements attached to the rotor thatcooperate with stationary elements. The stationary elements are referredto as concaves. The concaves surround the rotor in a rotor cage.Threshing and separating is accomplished by a combination of impact andrubbing action. As the rotor rotates, the grain crop is forced through agap between the rotor and the concaves and begins a spiral path throughthe front (threshing) section and then through the rear (separating)section towards the exit area of the rotor/concave system. The impactand rubbing action causes the grains to be detached. By the time thecrop is at the exit area almost all the grain has been separated fromthe MOG. The term for any grain that is remaining is called rotor loss.There are also other losses that can be attributed to the rotor/concavesystem, this is known as damaged grain loss (broken or cracked kernels).

As with any machine, performance is the key to efficiency. As mentionedabove, performance of the threshing mechanisms is measured by: Threshingefficiency; Separating efficiency; and Grain damage. The machineoperator has several means to adjust the threshing/separating efficiencyvs. grain damage equation. The speed at which the rotor turns (RPM) isadjustable, the gap between the rotor and the concaves is adjustable,and the crop feed rate can be adjusted simply by running more or, lessmaterial into the machine. Also, the condition of the crop itself canhave a dramatic effect on the loss vs. damage ratio. Crop moisturecontent, crop maturity, and crop type profoundly affect the machineperformance. Along with all these variables and possible adjustments,the operator still might not get the machine to perform to acceptablelevels of grain separated from the MOG during threshing. Indeed,producers are penalized for grain deliveries having MOG beyondacceptable levels. At this point the owner or operator may start lookingat threshing/separating components they might install in place ofconventional components.

Typically, new rotary combine harvesters will have installed a standardset of concaves, depending on the original equipment manufacturer.Present difficulties with current designs include concaves which do notsufficiently or properly separate the grain from MOG as the cropmaterial continues its spiral flow.

BRIEF SUMMARY OF THE INVENTION

In one aspect, an embodiment of the invention provides a concave sectionfor a harvester. The concave section has a concave body having anupstream side, a downstream side, a leading end and a trailing end. Theconcave body defines an arcuate crop engagement face facing radiallyinwardly. A plurality of crop passage openings are defined through thearcuate crop engagement face. A cover is configured to at leastpartially cover at least some of the crop passage openings. The cover iscarried by the concave body and movable thereon between at least twodifferent positions to adjust a degree of openness of at least some ofthe crop passage openings.

A slide assembly may secure the cover to the concave body. The cover maybe slideable relative to the concave body to selectively cover at leastsome of the crop passage openings.

A lock member may be arranged to lock the position of the cover amongthe at least two different positions and fix the degree of openness whenlocked. The lock member has an unlocked position allowing slidingmovement.

In an embodiment, the lock member comprises a clamp supported by theconcave body, releasably clamping the cover to the concave body.

A drive portion may be provided on the cover that is actuable to allowmovement of the cover relative to the concave body.

In an embodiment, the drive portion comprises at least one drive lugprovided by the cover.

In an embodiment, a leverage member may be arranged relative to thedrive lug in a spaced relationship that allows manual adjustment using atool acting upon the drive lug and the leverage member.

In an alternative embodiment, an actuator is arranged for remoteautomated position control of the cover relative to the concave body tocontrol the degree of openness.

A plurality of rub bars may define the arcuate crop engagement face. Therub bars extend laterally between the upstream side and the downstreamside and are arranged in spaced relation between the leading andtrailing end. The openings are defined between adjacent rub bars. Thecover is disposed radially outwardly of the rub bars.

In an embodiment, an arcuate support plate is radially outboard of therub bars and supporting the rub bars. The arcuate support plate furtherdefines the arcuate crop engagement face. The arcuate support platedefines the crop passage openings with a plurality of slots that arecoverable between adjacent pairs of rub bars. The cover is disposedradially outwardly of the arcuate support plate.

In another embodiment, the arcuate crop engagement face can be providedby a concave arrangement of rub bars alone.

The cover may define a plurality of corresponding slots, with a solidcover portion extending between corresponding slots, wherein thecorresponding slots are arranged to align with the slots of the arcuateplate to allow passage of crop material, and wherein the solid coverportion at least partially covers the slots of the arcuate plate to atleast partially close the slots of the arcuate plate.

In an embodiment, the cover includes a slotted cover plate. The arcuateplate of the concave section has a first radial thickness of between 2and 6.5 centimeters. The slotted cover plate has a second radialthickness of between 1 and 4 centimeters. The second radial thickness isthinner than the first radial thickness by between 10 and 75% of thefirst radial thickness. Advantageously, the cover's thinness minimizesweight increase to make the concave section serviceable.

In an embodiment, the concave body includes an upstream side plateproviding the upstream side, a downstream side plate providing thedownstream side, a leading end assembly providing the leading end and atrailing end assembly providing the trailing end. The upstream sideplate and the downstream side plate extend in parallel relation betweenthe leading end assembly and the trailing end assembly, and wherein thearcuate crop engagement face extends laterally between the upstream sideplate and the downstream side plate with the cover comprising a slottedarcuate plate arranged behind the arcuate crop engagement face.

Retainers may retain the slotted arcuate plate to the concave body. Theslotted arcuate plate is slidable relative to concave body whileretained thereto by the retainers.

In an embodiment, the retainers comprise a plurality of shoulder boltshaving head portions over the slotted arcuate plate to retain theslotted arcuate plate to the concave body. A lock fastener releasablylocks the slotted arcuate plate to the concave body.

The retainers can guide sliding movement of the arcuate plate in acircumferential direction between the leading end and the trailing endto adjust the degree of openness.

Preferably, the cover has a fully open position on the concave bodymaintaining the crop passage openings at the degree of openness that isfully open and a closed position on the concave body maintaining thecrop passage openings at the degree of openness that is fully closed.

Preferably, the cover is further movable on the concave body between atleast one intermediate position between fully open and closed positions.The cover when in at least one intermediate position only partiallycovers at least some of the crop passage openings.

Also preferably, the cover is configured to at least partially cover allof the crop passage openings.

In an embodiment, a harvester is provided that includes the concavesection. The harvester includes a bin. The harvester has a head at afront of the vehicle for engaging a crop to remove crop material. Arotor is interposed between the bin and the head. The rotor is proximatethe concave section in a concave region. The concave region includes atleast four concave sections arranged in downstream fashion from leadingthreshing concaves closest to the head to trailing separating concavesfarthest from the head. The rotor has a spiral engaging element facingthe concave sections operable to impart a rotational spiral flow of cropmaterial against a first of the four leading threshing concaves. Thedegree of openness controls and optionally limits an amount of threshingoccurring in leading threshing concaves.

The concave section with the cover feature is particularly advantageouswhen located in the threshing region of the concave region where controlover separation is more advantageous.

In another aspect, an embodiment of the invention provides a concavesection for a harvester that includes a concave body defining aplurality of crop passage openings. The concave section also includes acover movably mounted to the concave body. The cover is movable betweena first position and a second position to selectively uncover or coverof at least some of the crop passage openings.

The first position may be a fully open position on the concave bodymaintaining the crop passage openings at the degree of openness that isfully open. The second position may be a closed position on the concavebody maintaining the crop passage openings at the degree of opennessthat is fully closed.

Preferably, the cover includes a plurality of intermediate positionsbetween fully open and closed positions. The cover when in at least oneintermediate positions only partially covers at least some of the croppassage openings. The cover with each intermediate position achieves adifferent level of partial coverage.

The cover may be infinitely adjustable relative to the concave body toallow infinite coverage adjustment of the crop passage openings.

The cover may include a slotted arcuate plate. Retainers retain theslotted arcuate plate to the concave body. The slotted arcuate plate isslideable relative to concave body while retained thereto by theretainers.

A lock member may be arranged to lock the position of the cover amongfirst and second positions and fix the degree of openness when locked.The lock member has an unlocked position allowing sliding movement.

The concave section can include means for manually or automaticallyactuating movement of the cover between first and second positions. Suchmeans may include a drive section that is manually actuable or anactuator.

In yet another aspect, an embodiment of the invention provides a concavesection for a harvester. The concave section includes a concave bodydefining a plurality of crop passage openings. The concave sectionincludes means for adjustably covering the crop passage openings.

In still another aspect, in an embodiment, the cover includes a firstcover portion and a second cover portion separated by a break such thatthe first cover portion and second cover portion are separate pieces ofthe cover.

In an embodiment, the cover in includes a first cover portion and asecond cover portion, the first cover portion moveable in a firstdirection towards the trailing end and a second direction towards theleading end wherein movement of the first cover portion does not movethe second cover portion.

In an embodiment, the second cover potions is moveable in the first andsecond directions and movement of the second cover portion in the firstand second directions does not move the first cover portion.

The means may adjustably cover the crop passage openings to completelyclose the crop passage openings.

The means may adjustably cover the crop passage opening to keep the keepthe crop passage openings completely open.

The means may adjustably cover the crop passage openings to partiallyclose the crop passage openings.

The means may include a cover movably mounted to the concave body. Thecover is movable to provide the at least partial open position for thecrop passage openings and the fully closed position for the crop passageopenings.

In an embodiment, the cover includes a first rail and a second rail anda perforated arcuate support plate, the arcuate support plate extendingbetween the first and second rails.

In an embodiment, the first and the second rails are slideable along anupstream side plate and a downstream side plate respectfully and extendthere along from proximate a leading end plate to a trailing end plateof the concave body.

Other aspects, objectives and advantages of the invention will becomemore apparent from the following detailed description when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification illustrate several aspects of the present invention and,together with the description, serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a perspective and partly schematic view of a harvester with anembodiment of a concave section according to the teachings of theinstant invention;

FIG. 2 is a perspective view of the concave section of FIG. 1 with anembodiment of a crop engagement face according to the teachings of theinstant invention;

FIG. 3 is a perspective view of an intermediate assembly of the concavesection of FIG. 2;

FIG. 4 is an enlarged view of the area “A” of the intermediate assemblyof FIG. 3;

FIG. 5 is a rear view of the concave section of FIG. 2 with the coverremoved;

FIG. 5A is a rear view of the cover of a portion of the arcuate plateand a portion of the concave section of FIG. 2;

FIG. 6 is a partial view of side of an arcuate support plate and theremoved cover of the intermediate assembly of FIG. 3;

FIG. 7 is a rear perspective view of the concave section of FIG. 2 in afully open first state that better illustrates the cover;

FIG. 7A is an enlarged view of the area taken about 7A in FIG. 7;

FIG. 8 is rear perspective view of the concave section of FIG. 2 in asecond fully closed state;

FIG. 8A is an enlarged view of the area taken about 8A in FIG. 8 furtherillustrating a manual means such as a drive lug or gear rack formovement of the cover that may be acted upon by a tool;

FIG. 9 is an enlarged partial rear perspective view of the concavesection of FIG. 2 in the second state and an automatic means formovement of the cover;

FIG. 10 is a front side perspective view of an alternative embodiment ofthe concave section for the harvester of FIG. 1 with a different cropengagement face; and

FIG. 10A is front side perspective view of the cover of the concavesection of FIG. 10A.

FIG. 11 is rear perspective view of the concave section of FIG. 2 withan alternative side rail arrangement;

FIG. 12 is a rear view of another embodiment of a concave section in anopen first state;

FIG. 13 is another rear view of the concave section of FIG. 12 but in aclosed second state; and

FIG. 14 is another rear view of the concave section of FIG. 12 but in apartially closed third state.

While the invention will be described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents as included within the spirit and scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a rotary combine harvester 100, that may be referredto herein as a harvester 100. The harvester 100 includes a vehicle 102having a bin 104 for storing harvested grain. The harvester 100 furtherincludes a head 106 at a front 108 of the vehicle 102 for engaging acrop to remove as much crop material as possible while retaining itsgrain.

The harvester 100 includes a threshing and separating system 110 whichcomprises a rotor 112 and a rotor cage 114 also referred to as a concaveregion. The rotor cage 114 defines a central rotor axis 116. Further,the rotor cage 114 defines a rotor cavity 118 which surrounds andreceives the rotor 112 for rotation about the central rotor axis 116.The rotor 112 is interposed between the bin 104 and the head 106. Therotor 112 has a spiral engagement element 120 facing the rotor cage 114and is operable to impart a rotational spiral flow of the crop materialagainst the rotor cage 114.

The rotor 112 also includes threshing elements 122 that extend radiallyaway from the central rotor axis 116 to define outermost peripheralsurfaces of the rotor 112. A gap 124 is defined between the rotor cage114 and outermost peripheral surfaces of the threshing elements 122. Thecrop material with its grain flows through the gap 124 from a rotorfront 126 to a rear 128 of the rotor 112 to separate the remaining cropmaterial from its grain. Each one of the threshing elements 122 ispositioned to cooperate with a respective crop engagement face (See e.g.130 at FIG. 2) of a concave section 132, arranged in the rotor cage 114.The impact and rubbing action between the threshing elements 122 and thecrop engagement face 130 (FIG. 2) cause the grain to be detached fromthe crop material. As discussed above, the gap 124 can be adjusted bychanging out the threshing element 122 to increase or decrease itsradial extension away from the central rotor axis 116. By the time thecrop is at the rear 128 of the rotor 112 almost all the grain has beenseparated from the crop material.

The thresher and separating system 110 generally varies in function asthe crop material proceeds from the rotor front 126 to the rear 128 ofthe rotor 112. The rotor cage 114 at the rotor front 126 can include athresher region 134 while the rotor cage 114 at the rear 128 can includea separation section 136 and a separator region 138.

The thresher region 134 can include a plurality of concave sections 132.The concave sections 132 have crop engagement faces 130 (FIG. 2)designed to separate the grain from the material other than grain. Thenumber of concave sections 132 can be increased or decreased within thethresher region 134 to increase or decrease the amount of desiredthreshing.

The separation section 136 can also include a plurality of concavesections similar to threshing concave 132 such as concave sections withseparator crop engagement faces 230 (FIG. 10) that differ in profilefrom those in the threshing region 134 so as to provide for a less harshaction on the grain relative to the threshing region 134. The moregentle separation provided by crop engagement faces 230 (FIG. 10)prevents damage to the grain that may be more vulnerable to damagebecause the material other than grain has been partially removed in thethresher region 134.

The separator region 138 is generally located at the rear 128 of therotor cage 114 downstream of the separator section 136 but may also belocated between thresher region 134 and separator sections 136. Theseparator region 138 may be made up of concave sections similar toconcave sections 132 or configurations as shown in FIG. 10 or similarstructures that can include elements such as tines. It is not the intentto describe more fully the separator region 138 as such separatorregions 138 and their location in thresher/separating systems aregenerally known and function to further the separation of grain from thematerial other than grain.

Use of the term “upstream” and “downstream” is relative to the flow ofcrop material from the rotor front 126 to the rear 128 of the rotor 114.The terms “leading” and “trailing” refer to a structure in rotation,here about central rotor axis 116. “Leading” and “trailing” is relativeto where the crop material first engages the concave section 132. Inother words, the crop material first engages the concave section 132 isleading and where the concave last engages the crop is “trailing.”

FIG. 2 illustrates the concave section 132 according to an embodiment ofthe instant invention. Concave section 132 includes a concave body 140defining an upstream side 142, a downstream side 144, a leading end 146and a trailing end 148. Upstream side plate 150 may provide the upstreamside 142 and downstream side plate 152 may provide the downstream side144. An arcuate support plate 160 extends between and may be coupled to,for example by weldment, to the upstream side plate 150 and downstreamside plate 152. Leading end plate assembly 154 couples the upstream sideplate 150 and the downstream side plate 152 at the leading end 146.Trailing end plate assembly 156 couples the upstream side plate 150 andthe downstream side plate 152 at trailing end 148.

Concave section 132 is arcuate to facilitate its placement in theharvester 100 (FIG. 1) around the central rotor axis 116. Accordingly,crop engagement face 130, upstream side plate 150 and downstream sideplate 152 are arcuate such that a radius extending from the centralrotor axis 116 provides their curvature/circumference. As illustrated,the upstream side plate 150 and the downstream side plate 152 extend inparallel relation between the leading end plate assembly 154 and thetrailing end plate assembly 156.

Rub bars 162 are indirectly coupled to the upstream and the downstreamsideplates 150, 152 via the arcuate support plate 160. Morespecifically, the arcuate support plate 160 defines weldment cut outs163 (FIG. 3) that advantageously lighten the overall weight of theconcave section 132 while providing mounting apertures to facilitateweldment of the rub bars 162. The rub bars 162 may be generallyrectangular in shape to maximize threshing. Crop passage openings 158can be defined between rub bars 162 and/or by the arcuate support plate160 and extend between the upstream and the downstream sideplates 150,152. Further, the crop passage openings 158 extend in rows betweenadjacent rub bars 162 from the first leading end 146 toward the firsttrailing end 156. Accordingly, in an embodiment, the crop engagementface 130 can be defined by the actuate support plate 160 with its croppassage openings 158 and the rub bars 162.

FIG. 3 illustrates an intermediate assembly of the concave section 132of FIG. 2. FIG. 3 illustrates the concave section 132 with the rub bars162 removed to reveal the weldment cut outs 163. Once the rub bars 162are welded to the arcuate support plate 162 the weldment cut outs arecompletely closed.

With reference now to FIG. 2 the crop engagement face 130 includes thearcuate support plate 160 providing the crop passage openings 158 andincludes the rub bars 162. In still further embodiments, the concavesection 132 may not include arcuate support plate 160. Where there is noarcuate support plate 160 the rub bars 162 may be directly coupled tothe upstream and the downstream side plates, 150, 152 such that the croppassage openings 158 are defined between adjacent rub bars 162, that is,the crop passage openings 158 are the gaps 164 having no solid portionsbetween adjacent rub bars 162. For example, this is described later withreference to FIG. 10.

The crop passage openings 158 typically have a wide range of area sizesof between 1 to 60 square centimeters. Where the crop passage openings158 are defined between adjacent rub bars 162, they typically areseparated at a spacing forming the gaps 164 of between 2 and 10centimeters between adjacent rub bars 162. As illustrated in FIGS. 2 and3, the crop passage openings 158 are formed as slots 166, they morepreferably have an area size between 1 to 12 square centimeters for mostgrain crops. Further, FIG. 4 illustrates the slots 166 have an elongatedlength 168 preferably between 0.5 and 8 centimeters and a slot width 170of between 0.3 and 3 centimeters, with typically a length to width ratioof between 1 and 5. In still further embodiments it is envisioned thatthe crop passage openings 158 may be round slots.

FIG. 5 illustrates a rear view of the concave section 132 of FIG. 2 witha cover 172 (FIG. 5A) removed such that the back of the arcuate supportplate and rub bars 162 are visible. With respect to FIGS. 5 and 5A, thecover 172 is a perforated arcuate plate 173 defining corresponding cropopenings 174. The cover 172 is arranged behind the crop engagement face130 that is arcuate (FIG. 2), that is, the cover 172 is arrangedradially outward/outboard of the arcuate support plate 160 relative tothe central rotor axis 116 (FIG. 1).

The cover 172 is carried by the concave body 140 and movable thereonbetween at least two different positions to adjust a degree of opennessof at least some of the crop passage openings 158. Therefore, the cover172 is configured to at least partially cover at least some of the croppassage openings 158. More specifically, corresponding crop openings 174preferably correspond to and match the same configuration and geometryas the crop passage openings 158. Accordingly, in the embodimentillustrated, the corresponding crop openings 174 are corresponding slots175 slots that are sized and arranged like the slots 166 defined by thearcuate support plate 160. Further, the cover 172 defines a solid coverportion 178 that extends between corresponding crop openings 174 fromthe leading end plate assembly 154 to the trailing end plate assembly156.

The corresponding crop openings 174 are arranged by movement of thecover 172 in a circumferential direction 176 relative to the arcuatesupport plate 160 to align with the slots 166 of the arcuate supportplate 160 to allow passage of crop material. By movement in acircumferential direction 176 it is meant towards and away from theleading end plate assembly 154. Accordingly, the cover 172 may be movedrelative to the arcuate support plate 160 to at least partially coverthe slots 166 of the arcuate support plate 160 to at least partiallyclose the slots 166 of the arcuate support plate 160.

However, rather than more circumferentially, in another embodiment thecover 172 could move laterally in the direction of the central rotoraxis 116.

In the illustrated embodiment involving a circumferentially moveablecover, the cover 172 includes a first rail 186 and a second rail 188 andthe perforated arcuate plate 173. The perforated support plate 173extends between the first and second rails 186, 188. The first and thesecond rails 186, 188 are adjustably moveable along the upstream anddownstream side plates 150, 152 and extend longitudinally from proximatethe leading end plate assembly 154 to proximate the trailing end plateassembly 156.

In an embodiment the perforated arcuate plate 173 is connected to thefirst and second rails 186, 188 by weldment. However, it is not theintent to limit connection via weldment as other means includingfasteners for example are envisioned. In yet other embodiments the firstand second rails 186, 188 and the perforated arcuate plate 173 may beintegral, that is, monolithic and thus formed together. Thus, in theembodiments envisioned, movement of the cover 172 includes movement ofthe first and second rails 186, 188 and the support plate 173 togetherin the same direction.

In yet other embodiments, the first and the second rails 186, 188 andthe perforated arcuate plate 173 are mounted behind the arcuate supportplate 160 such that movement of the cover 172 in a transverse direction190, that is, in a direction such that the cover 172 moves toward oraway from the upstream and downstream side plates 150, 152 relative tothe arcuate support plate 160 results in a fully open area, fully closedarea, or a partially open and partially closed area. By fully open areait is meant the crop material is allowed to pass through the croppassage opening 158 and the corresponding crop openings 174 withoutobstruction by the solid cover portion 178. By fully closed area it ismeant that none of the crop material is allowed to pass completelythrough the crop passage openings 158 and the corresponding cropopenings 174 because the solid cover potion 178 sufficiently blocks thecrop passage openings 158.

Intermediate positions for the cover 172 are also possible to control adegree of openness between the fully open position and the fully closedposition to allow some material passage but less than fully open. Inother words, the cover 172 may only partially cover the crop passageopening 158. Indeed, each of the intermediate positions of the cover 172provide a different level of partial coverage of the crop passageopenings which correlates to a different degree of openness providedwith each intermediate position to control the amount of grain passingtherethrough.

FIG. 6 is a partial perspective view of the upstream side 144 of thearcuate support plate 160 and the cover 172. For illustrative purposes,the cover 172 has been removed from behind the actuate support plate160. The arcuate support plate 160 has a first radial thickness 180 ofbetween 2 and 6.5 centimeters. The arcuate support plate 160 plate has asecond radial thickness 182 of between 1 and 4 centimeters. The secondradial thickness 182 is thinner than the first radial thickness 180 bybetween 10 and 75% of the first radial thickness, and typically by atleast 50% thinner.

The cover 172 presents a light weight solution taking up limited spaceto provide an advantageous solution for controlling the amount ofthreshing by presenting greater or less open area through movement ofthe cover 172 relative to the arcuate support plate 160. Closing theopen the area provided by the arcuate support plate 160 with the cover172 increases the amount of threshing as the grain or other materialcannot escape through the corresponding crop openings 174 as readily andis thereby subject to more threshing and thus greater separation of thegrain from the material other than grain. Conversely, providing moreopen area decreases the amount of threshing.

FIGS. 7 illustrates a rear perspective view of the downstream side 144of the concave section 132 of FIG. 2. FIG. 7 illustrates the cover 172in a first state, which in this case is a fully open state. In the fullyopen state, the corresponding crop openings 174 are aligned with thecrop passage openings 158 such that a threshed grain can pass throughthe entire crop passage opening 158 (FIG. 3) without obstruction by thesolid cover portion 178. A slide assembly 192 secures the cover 172 tothe concave body 140 to permit the cover 172 to be slideable relative tothe concave body 140 to selectively cover at least some of the croppassage openings 158. The slide assembly 192 may be partially integratedinto the cover (e.g. the rails 186, 188) and the concave body 140 (e.g.retainers).

The upstream side 142 may provide part of the slide assembly 192 that isstructurally the same part on the downstream side 144. Slide assemblyportions may be arranged to mirror those on the downstream side, but inembodiments, they may be arranged independently of the other. In anembodiment there may be between 1 and 10 slide assembly 192 componentlocations on each one of the upstream and downstream sides 142, 144. Ina preferred embodiment there may be between 2 and 8 slide assembly 192component locations on each one of the upstream and downstream sides142, 144. In a more preferred embodiment there may be between 4 and 6slide assembly 192 component locations on each one of the upstream anddownstream sides 142, 144.

The slide assembly 192 may include a retainer slot 194 that in anembodiment may be defined by the rails 186, 188. The slide assembly 192includes retainers such as a pin 196 for slideably securing the cover172 to the concave body 140.

The retainer slot 194 may be in the form of an arcuate slot having adegree of curvature matching that of the arcuate support plate 160 (FIG.3) and the cover plate 172. The retainer slot 194 has a first end 198nearest the leading end plate assembly 154 and a second end 200 nearerthe trailing end plate assembly 156. As illustrated, the cover 172 hasbeen slid towards the trailing end plate assembly 156 to position firstend 198 of the retainer slot 194 against the pin 196 to provide a fullyopen position for all the crop passage openings 158. Ends of theretainer slots may provide stops limiting movement and/or the cover 172may also bottom out against structures 154, 156.

The retainer pin 196 may be any number of structures, for example ashoulder bolt or a bolt. In the embodiment illustrated a threadedportion of the shoulder bolt has passed through the retainer slot 194 tobe received by the downstream side plate 152. A head 202 on the shouldbolt 196 has an outmost diameter exceeding that of the retainer slot 194so as to keep the first rail 186 of the cover 172 slideably secured tothe downstream side plate 152 of the concave body 140. Accordingly, thefirst rail 186 is sandwiched between the head 202 of the shoulder bolt196 and the downstream side plate 152 to permit slideable movement ofthe retainer slot 194 under the head 202.

Further, a lock member 204 is arranged to lock the position of the cover172 among the at least two different positions and fix the degree ofopenness when locked. The lock member 204 can be engaged and disengagedto provide an unlocked position allowing sliding movement of the cover172. In the embodiment illustrated the lock member 204 is a fastener,also referred to as a lock fastener 204. The lock fastener 204 isthreaded at one end and has a fastener head 206 at the other end.Turning the lock fastener 204 in a first direction such as within one ofthe retainer slots 194 loosens the fitment between the first rail 186 ofthe cover 172 and the downstream sideplate 152 such that the first rail186 may be slid relative to the arcuate support plate 160 to provide fora greater or lesser degree of openness as desired. Turning the lockfastener 204 in the second direction locks the first rail 186 of thecover 172 against the downstream sideplate 152 to clamp and preventslideable movement during use of the concave section 132. It is not theintent to limit embodiments to only fasteners, as other lockingmembers/means are envisioned, for example, the lock member 204 may be adifferent type of clamp supported by the concave body 140, releasablyclamping the cover 172 to the concave body 140.

FIGS. 7 and 7A illustrate a drive portion 206 on first rail 186 of thecover 172. The drive portion 206 may be located on one of or both thefirst and second side rails 186, 188 of the cover 188 (FIG. 6). Further,the first and second drive rails 186 in an embodiment may be definerespective drive portions 206 that may be in the form of a gear rackcomprising one or more drive lugs 208. The drive portion 206 is actuableto allow movement of the cover 172 relative to the concave body 140. Byactuable it is meant that a force may be applied thereto to slide thecover 172 when in an unlocked position. The drive portion 206 maycomprise at least one drive lug 208 provided by the cover 172.

A leverage member 210 is arranged relative to the drive lug 208 in aspaced relationship that allows a mechanic to manually adjust using atool 212 (e.g. prybar or screwdriver) acting upon the drive lug 208 andthe leverage member 210. More specifically, the leverage member 210 maybe located on either or both of the upstream and downstream side plates150, 152 generally proximate the drive portions 206 of the cover 172.

FIG. 8, as with FIG. 7, illustrates a rear perspective view of thedownstream side 144 of the concave section 132 of FIG. 2. However, FIG.8 illustrates the cover 172 in a second state, also referred to as afully closed state. In the fully closed state, the solid cover portion178 is aligned to prevent threshed grain or MOG from passing through thecrop passage openings 158 or the corresponding crop passage openings174. Only the solid portion 178, the back of rub bars 162 are seenthrough crop passage openings 158. As illustrated, the cover 172 hasbeen slid away from the trailing end plate assembly 156 and towards theleading end plate assembly 154 to position second end 200 of theretainer 194 against the pin 196.

FIG. 8A is an enlarged view of the area taken about the drive portion206 of FIG. 8. Thus, FIG. 8A also illustrates the cover in a secondstate, wherein the plurality of crop passage openings 158 are fullyclosed. A tool 212 is illustrated acting upon the drive lug 208 and theleverage member 210 to move the cover 172 to the second state. As cannow be readily appreciated, the cover 172 maybe slideably moved to atleast one intermediate position only partially covering at least some ofthe crop passage openings 158. The cover 172 maybe moved to furtherintermediate positions between fully open and closed positions topartially cover at least some of the crop passage openings 158 with eachintermediate position achieving a different level of partial coverage.Preferably, the cover 172 is infinitely adjustable relative to theconcave body 140 to allow infinite coverage adjustment of the croppassage openings 158. However, discrete or stepped positions are alsopossible and may be marked on the concave section to correspond toselect openness

FIG. 9 illustrates an embodiment of the concave section 132 with thecover in a fully closed position utilizing an actuator 214 to engage thedrive portion 206 to move the cover 172 either towards or away from theleading end plate assembly 154 to acquire the desired degree of opennessof the crop passage openings 158 (FIG. 3). Such adjustmentadvantageously allows for the amount of threshing by adjusting theconcave sections 132 in the harvester 100 (FIG. 1) without having toremove them from the harvester 100 and thereby advantageously savingtime otherwise spent in removing the concave sections 132. Accordingly,manual means, such as the gear rack, drive lug 208 or a handle or otherengagement surface can be provided by the cover 172 arranged and sizedto acted upon by the tool 212 or operator to facilitate movement; and/oran actuator 214 may be utilized such as an electric, hydraulic orpneumatic servo actuator or stepper motor that acts on the cover 172 forautomatic means.

FIG. 11 illustrates the concave section 132 but with an alternativearrangement for the first and second rails 186, 188. The samearrangement to be discussed relative to first rail 186 is applicable tosecond rail 188 (FIG. 7) although only first rail 186 is illustrated inFIG. 11. In this alternative arrangement, first rail 186 includes afirst drive portion 185 separated and spaced apart from a first guideportion 187. The first drive portion 185 includes the drive portion 206.The first drive portion 185 may be attached, via weldment for example tothe cover 172 or it may be integral therewith by way of non-limitingexample. The first guide portion 187 may be fixed to upstream side plate150 by weldment or other known means such that it acts as a slottedguide for the cover 172. Use of drive lug 208 in relation to driveportion 206 may be by manual or automated means as previously discussed.

FIG. 10 illustrates a concave section with a second embodiment of thecrop engagement face 232 with a cover 272 (FIG. 10A) removed from behindthe crop engagement face 232. The concave section of FIG. 10 is utilizedin separator section 136 (FIG. 1). Crop engagement face 230 is similarin most respects to crop engagement face 130 (FIG. 2) except for thedifferences explained here. Crop engagement face 232 includes round bars262, as previously discussed provide for a gentle separation of thegrain from the material other than grain. The round bars 262 are usedinstead of the edged rub bars 162 (FIG. 2). Further, instead of thearcuate support plate 160 defining the crop passage openings 158, spacedapart adjacent round bars 262 define the crop passage openings 258 ofthe crop engagement face 230. Additionally, as can now be readilyappreciated a cover 272 is located behind the round bars 262. The cover272, defines corresponding crop openings 274 orientated in a patternsimilar to that of the crop passage openings 258 with solid coverportion 278. Accordingly, as with the cover 170, cover 272 is moveableto infinitely adjustable the degree of openness of the crop passageopenings 258.

Although not illustrated, it may now be readily understood that variousembodiments utilizing a moveable cover can be used to match concaveshaving diverse crop engagement faces. Indeed, where a crop engagementface may utilize both rub bars and round bars but does not utilize anarcuate support plate, a cover plate can be provided behind the cropengagement face to control the degree of openness. Further, where a cropengagement face includes an arcuate support plate with rub bars, a covercan still be provided to inexpensively, control the degree of opennesswith an elegant light weight solution taking up minimal space in theharvester 100 (FIG. 1) to improve the amount of grain separated frommaterial other than grain harvested and with the least amount of damage.

FIGS. 12 is a rear view of another embodiment of a concave section 300in a fully open first state. Concave section 300 is the same as theconcave section 132 except cover 302 differs from cover 172 as describedherein and as seen in FIG. 12. Cover 302 includes a first cover portion304 and a second cover portion 306 which define break 308 between thefirst cover portion 304 and the second cover portion 306. The break 308divides the cover 302 in different areas and preferably equal areas viaseparate pieces that are moveable independent of one another. Each coverportion 302 or 304 may be considered a “cover.” For example, if only oneof the two cover portions 302 or 304 is used, it is thereby covered,literally, by the broadest claims appended here to.

The break 308 runs in a direction that is transvers to a longitudinalaxis 310 bisecting the trailing end plate assembly 312 and the leadingend plate assembly 314. It can be readily appreciated that the break 308may be perpendicular to the longitudinal axis 310 or of any orientationsuch that corresponding crop openings 316 are aligned to match analternative crop engagement face on the front of the concave section 300and/or an alternative arcuate support plate having a differentarrangement of crop passage openings 318. As illustrated in the fullyopen position, the first cover portion 304 and the second cover portion306 are aligned such that the crop openings 318 are in line with thecorresponding crop openings 316 allowing for grain to pass therethrough.

A plurality of first slide assemblies 320, positioned and functioning asslide assembly 192 (FIG. 7), secure the first cover portion 304 to theconcave body 322 and permit the first cover portion 304 to be slideablerelative to the concave body 322 to selectively cover at least some ofthe crop passage openings 318.

First drive portions 324 are independently actuable utilizing firstleverage members 326 which are positioned and function similar toleverage members 210 (FIG. 7) to allow for movement of the first portion304 relative to the concave body 322 and the second portion 306. Byindependently actuable it is meant that actuation of any one of thesingle drive portions 324, for example by a tool (FIG. 8) or actuator(FIG. 9), is enough to move the first portion cover 304 and withoutmovement of the second cover portion 306.

The first cover portion 304 is slideable in first and second directionsparallel to the longitudinal axis 310. The first direction is movementtowards the trailing end plate assembly 312 and the second direction ismovement towards the leading end plate assembly 314. The first slideassemblies 320 limit the distance the first cover portion 304 moves inthe first and second directions. In the fully open state, the firstcover portion 304 has moved in the second direction towards the leadingend plate assembly 314 to the maximum extent permitted by the firstslide assemblies 320.

The second cover portion 306 is slideable in the first direction and thesecond directions parallel to longitudinal axis 310. Second driveportions 328 are independently actuable utilizing second leveragemembers 330 to move the second cover portion 306 in the first and seconddirections relative to the concave body 322 and the first cover portion304. It should be readily apparent at this point that the first coverportion 304 and second cover portion 306 are moved independently of oneanother. Movement of the second cover portion 306 in the first andsecond directions is limited by second slide assemblies 332. In thefully open position the second cover portion 306 has been moved in thefirst direction towards the trailing end plate assembly 312 to themaximum extent permitted by the second slide assemblies 332.

In the fully open state, the corresponding crop openings 316 are alignedwith the corresponding crop passage openings 318 such that threshedgrain can pass through the entire crop passage opening 316 andcorresponding crop passage openings 318 with minimal obstruction bysolid portions of the first portion 304. By minimal it is meant thatless than 5% of the crop passage openings 316 are obstructed. In apreferred embodiment less than 3% are obstructed and in a more preferredembodiment less than 1% are obstructed.

With attention now to FIG. 13, a second state of the concave section 300is illustrated. The second state is a fully closed state wherein thefirst cover portion 304 has been moved in the first direction towardsthe trailing end plate assembly 312 to the greatest extent possible aslimited by the first slide assemblies 320. The second cover portion 306has been moved in the second direction, opposite the first direction,towards the leading end plate assembly 314 to the greatest extentpossible as limited by the second slide assemblies 332. Thus, in theembodiment illustrated over 75% of the crop passage openings 316 arecompletely closed by solid portions of the first cover portion 304 andthe second cover portion 306 of the cover 302. In a preferred embodiment80% of the crop passage openings 316 are completely closed and in apreferred embodiment 90% or more of the crop passage openings 316 arecompletely closed.

FIG. 14 illustrates a third state of the concave section 300. In thethird state the first cover portion 304 has been moved in the firstdirection towards the trailing end plate assembly 312 to partially closethe crop passage openings 316 and the second cover portion 306 has beenmoved in the second direction towards the leading end plate assembly 314to partially close the crop passage openings 316. Retainer slots (seeFIG. 7A at 192) of each the first slide assemblies 320 allow formovement of the first cover portion 304 in the first and seconddirections as limited by the retainer slots first and second ends. Thus,the first cover portion 304 is moveable in the first and seconddirections to positions proportional to the positions and distancesbetween the first and second ends.

So too, the retainer slots (see FIG. 7A at 192) of each the second slideassemblies 332 allow for movement of the second cover portion 306 in thefirst and second directions as limited by the retainer slots first andsecond ends. Thus, the second cover portion 306 is moveable in the firstand second directions to positions proportional to the positions anddistances between the first and second ends.

Thus, it should be readily understood at this point that because thefirst cover portion 304 and the second cover portion 306 are moveable tomany positions to cover and uncover the total area provide by the croppassage openings 316 then it provides the operator with a continuum ofpositions for the first cover portion 304 and the second cover portion306 to adjust the threshing/separating efficiency vs. grain damageequation to optimize harvesting efficiency.

Cover 302 with the first cover portion 304 and second cover portion 306,also referred to as a segmented cover, allows for multi-threshingcapability within a single concave 300 as well as among concaves 300. Itis believed an additional benefit provided by the segmented cover 302 isthat it will provided for more even distribution across the harvester'scleaning system, also referred to a cleaning shoe to provide forimproved harvester efficiency. Further, the segmented cover 302 requiresless force to adjust the position of the cover 302 relative to a singlecover 172 (FIG. 7). Thus, the force to overcome friction resulting fromcrop residue is reduced and mass requiring movement is reduced.

All references, including publications, patent applications, and patentscited herein are hereby incorporated by reference to the same extent asif each reference were individually and specifically indicated to beincorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) is to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

What is claimed is:
 1. A concave section for a harvester, comprising: aconcave body having an upstream side, a downstream side, a leading endand a trailing end, and defining an arcuate crop engagement face facingradially inwardly; a plurality of crop passage openings defined throughthe arcuate crop engagement face; a cover configured to at leastpartially cover at least some of the crop passage openings, the covercarried by the concave body and movable thereon between at least twodifferent positions to adjust a degree of openness of at least some ofthe crop passage openings.
 2. The concave section of claim 1, furthercomprising a slide assembly securing the cover to the concave body, thecover being slideable relative to the concave body to selectively coverat least some of the crop passage openings.
 3. The concave section ofclaim 2, further comprising a lock member arranged to lock the positionof the cover among the at least two different positions and fix thedegree of openness when locked, the lock member having an unlockedposition allowing sliding movement.
 4. The concave section of claim 3,wherein the lock member comprises a clamp supported by the concave body,releasably clamping the cover to the concave body.
 5. The concavesection of claim 1, further comprising a drive portion on the cover, thedrive portion being actuable to allow movement of the cover relative tothe concave body.
 6. The concave section of claim 5, wherein the driveportion comprises at least one drive lug provided by the cover.
 7. Theconcave section of claim 6, further comprising a leverage memberarranged relative to the drive lug in a spaced relationship that allowsmanual adjustment using a tool acting upon the drive lug and theleverage member.
 8. The concave section of claim 5, further comprisingan actuator arranged for remote automated position control of the coverrelative to the concave body to control the degree of openness.
 9. Theconcave section of claim 1, wherein by a plurality of rub bars definethe arcuate crop engagement face, the rub bars extending laterallybetween the upstream side and the downstream side and arranged in spacedrelation between the leading and trailing end, the openings beingdefined between adjacent rub bars, and wherein the cover is disposedradially outwardly of the rub bars.
 10. The concave section of claim 9,further comprising an arcuate support plate radially outboard of the rubbars and supporting the rub bars, the arcuate support plate furtherdefining the arcuate crop engagement face, the arcuate support platedefining the crop passage openings with a plurality of slots that arecoverable between adjacent pairs of rub bars, wherein the cover isdisposed radially outwardly of the arcuate support plate.
 11. Theconcave section of claim 9, wherein the cover defines a plurality ofcorresponding slots, with a solid cover portion extending betweencorresponding slots, wherein the corresponding slots are arranged toalign with the slots of the arcuate plate to allow passage of cropmaterial, and wherein the solid cover portion at least partially coversthe slots of the arcuate plate to at least partially close the slots ofthe arcuate plate.
 12. The concave section of claim 9, wherein the covercomprises a slotted cover plate, wherein the arcuate plate has a firstradial thickness of between 2 and 6.5 centimeters; wherein the slottedcover plate has a second radial thickness of between 1 and 4centimeters; and wherein second radial thickness is thinner than thefirst radial thickness by between 10 and 75% of the first radialthickness.
 13. The concave section of claim 1, wherein the concave bodycomprises: an upstream side plate providing the upstream side, adownstream side plate providing the downstream side, a leading endassembly providing the leading end a trailing end assembly providing thetrailing end, wherein the upstream side plate and the downstream sideplate extend in parallel relation between the leading end assembly andthe trailing end assembly, and wherein the arcuate crop engagement faceextends laterally between the upstream side plate and the downstreamside plate, the cover comprising a slotted arcuate plate arranged behindthe arcuate crop engagement face.
 14. The concave section of claim 13,comprising retainers retaining the slotted arcuate plate to the concavebody, the slotted arcuate plate being slidable relative to concave bodywhile retained thereto by the retainers.
 15. The concave section ofclaim 14, wherein the retainers comprise a plurality of shoulder boltshaving head portions over the slotted arcuate plate to retain theslotted arcuate plate to the concave body, and a lock fastenerreleasably locking the slotted arcuate plate to the concave body. 16.The concave section of claim 14, wherein the retainers guide slidingmovement of the arcuate plate in a circumferential direction between theleading end and the trailing end to adjust the degree of openness. 17.The concave section of claim 1, wherein the cover has a fully openposition on the concave body maintaining the crop passage openings atthe degree of openness that is fully open and a closed position on theconcave body maintaining the crop passage openings at the degree ofopenness that is fully closed.
 18. The concave section of claim 17,wherein the cover is further movable on the concave body between atleast one intermediate position between fully open and closed positions,the cover when in at least one intermediate position only partiallycovering at least some of the crop passage openings.
 19. The concavesection of claim 1, wherein the cover is configured to at leastpartially cover all of the crop passage openings.
 20. A harvesterincluding the concave section of claim 1, the harvester including avehicle having a bin; a head at a front of the vehicle for engaging acrop to remove crop material; a rotor interposed between the bin and thehead, the rotor proximate the concave section in a concave region, theconcave region comprising at least 4 concave sections arranged indownstream fashion from leading threshing concaves closest to the headto trailing separating concaves farthest from the head, the rotor havinga spiral engaging element facing the concave section operable to imparta rotational spiral flow of crop material against a first of the fourleading threshing concave; and wherein the degree of openness controlsand optionally limits an amount of threshing occurring in said one ofthe leading threshing concaves.
 21. A concave section for a harvester,comprising: a concave body defining a plurality of crop passageopenings; a cover movably mounted to the concave body, the cover beingmovable between a first position and a second position to selectivelyuncover or cover of at least some of the crop passage openings.
 22. Theconcave section of claim 21, wherein the first position is a fully openposition on the concave body maintaining the crop passage openings atthe degree of openness that is fully open and the second position is aclosed position on the concave body maintaining the crop passageopenings at the degree of openness that is fully closed.
 23. The concavesection of claim 22, further comprising a plurality of intermediatepositions between fully open and closed positions, the cover when in atleast one intermediate positions only partially covering at least someof the crop passage openings, with each intermediate position achieve adifferent level of partial coverage.
 24. The concave section of claim23, wherein the cover is infinitely adjustable relative to the concavebody to allow infinite coverage adjustment of the crop passage openings.25. The concave section of claim 21, the cover including a slottedarcuate plate, the concave section further comprising retainersretaining the slotted arcuate plate to the concave body, the slottedarcuate plate being slideable relative to concave body while retainedthereto by the retainers.
 26. The concave section of claim 21, furthercomprising a lock member arranged to lock the position of the coveramong first and second positions and fix the degree of openness whenlocked, the lock member having an unlocked position allowing slidingmovement.
 27. The concave section of claim 21, further comprising meansfor manually or automatically actuating movement of the cover betweenfirst and second positions.
 28. A concave section for a harvester,comprising: a concave body defining a plurality of crop passageopenings; means for adjustably covering the crop passage openings. 29.The concave section of claim 28, wherein the means adjustably cover thecrop passage openings to completely close the crop passage openings. 30.The concave section of claim 28 wherein the means adjustably cover thecrop passage openings such that the crop passage openings are completelyopen.
 31. The concave section of claim 28, wherein the means comprises acover movably mounted to the concave body, the cover being movable toprovide the at least partial open position for the crop passage openingsand the fully closed position for the crop passage openings.
 32. Theconcave section of claim 31, wherein the cover includes a first rail anda second rail and a perforated arcuate support plate, the arcuatesupport plate extending between the first and second rails.
 33. Theconcave of claim 32, wherein the first and the second rails areadjustable along an upstream side plate and a downstream side plate andextend there along from proximate a leading end plate to a trailing endplate of the concave body.
 34. The concave section of claim 1, whereinthe cover is a segmented cover that includes a first cover portion and asecond cover portion separated by a break such that the first coverportion and second cover portion are separate pieces of the cover. 35.The concave section of claim 1, wherein the cover is a segmented coverincluding a first cover portion and a second cover portion, the firstcover portion moveable in a first direction towards the trailing end anda second direction towards the leading end wherein movement of the firstcover portion does not move the second cover portion.
 36. The concavesection of claim 35, wherein the second cover portion is moveable in thefirst and second directions and wherein movement of the second coverportion in the first and second directions does not move the first coverportion.